What is remarkable about the Tenderloin is that it has remained physically unchanged for more than 80 years. It is a time capsule. The same progressive forces that have kept out ‘progress’ and inadvertently created a Museum of Depravity, have also created a Museum of the Lost City, a vanished world memorialized in the neighborhood’s extraordinary collection of residential hotels. There are hundreds of these historic SROs in the Tenderloin, the largest number in the world. The SROs are the reason that in 2008, the Uptown Tenderloin was placed on the National Register of Historic Places, the 24th San Francisco neighborhood to be so listed.